In the present work, room temperature hydrogen sensing properties of platinum (Pt) and platinum-iron (Pt<inf>3</inf>Fe) alloy nanoparticle (NP) decorated nitrogen doped graphene were investigated. In order to incorporate the nitrogen functional groups within the graphene matrix, first graphene was coated with the nitrogen anionic polyelectrolyte followed by the pyrolysis in inert atmosphere. Further Pt and Pt<inf>3</inf>Fe nanoparticles were decorated on nitrogen-doped graphene (NG) by modified polyol reduction technique. The systemic investigation of hydrogen sensing properties of Pt/NG and Pt<inf>3</inf>Fe/NG NPs at 4 vol% of hydrogen reveals the excellent sensitivity of these composites. The present study shows that Pt<inf>3</inf>Fe/NG NPs composite can be believed as a high performance room temperature sensing material. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Sundara Ramaprabhu

Department Of Physics

Mridula Baro

Santhosh P Nagappan Nair

Alloys

Chemical sensors

Doping (additives)

Functional groups

Graphene

Hydrogen

Iron

Iron alloys

Nanoparticles

nitrogen

Platinum

Polyelectrolytes

Temperature sensors

ALLOY NANOPARTICLE

ANIONIC POLY-ELECTROLYTES

HYDROGEN SENSING PROPERTIES

Hydrogen Sensor

NITROGEN DOPED GRAPHENE

NITROGEN FUNCTIONAL GROUPS

PLATINUM-IRON ALLOYS

ROOM TEMPERATURE SENSING

Platinum alloys

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

International Journal of Hydrogen Energy

The uniqueness in the physical and electrochemical properties and the structural integrity towards lithium ion storage make carbon nanotubes (CNT) a viable anode material for the lithium ion battery. But the morphology dependent electrochemical performance and high irreversibility in capacity stand as stumbling blocks to its commercialization. Herein, we demonstrate that irreversible capacity and short cycle life in CNT based anode material can be eliminated by exfoliation of a few of its outer layers with the incorporation of sulfur. The incorporation of sulfur brings in two lithium ion storage mechanisms in the electrode, insertion and sulfur redox reaction. We have observed this phenomenon by cyclic voltammetry and the corresponding behavioral change by dynamic electrochemical impedance spectroscopy. The assembled battery has been tested for various current densities from 150 to 40 000 mA g−1. The cell retained a capacity of 200 mA h g−1 for 7370 cycles at 10 000 mA g−1, proving the capability of the material for long cycle life even at higher current densities. The ultrahigh capacity of 1120 mA h g−1 at 150 mA g−1 after 10 000 cycles reveals its great potential as an anode material for commercial lithium ion batteries. © The Royal Society of Chemistry.

Journal of Materials Chemistry A

Binary reaction ingrained high current density and long cycle life novel anode material for lithium ion battery

Graphene Oxide-Molecular Imprinted Polymer (GO-MIP) based electrochemical sensor was developed for the first time towards enzyme less determination of glucose. This GO-MIP was obtained from a series of fictionalization, polymerization and template molecule introduction/removal during the synthesizing process. The proposed GO-MIP based electrode showed excellent electrocatalytic activity towards glucose oxidation at optimized conditions and possessing detection limit of 0.1 nM with a response time of ~ 2 min. The current response of GO-MIP based glucose sensor was linearly related to the concentration of glucose. The results obtained from the real time usability of electrodes in human blood matches well with commercially available glucose monitors. Further, the reusability of the material is checked up to eight cycles and interference of glucose with ascorbic acid (AA), uric acid (UA) and dopamine (DA) were also studied. The obtained results endorse the promising application of GO-MIP towards superior glucose sensing with long term stability. © 2017 Elsevier B.V.

Materials Science and Engineering C

Highly sensitive and selective non enzymatic electrochemical glucose sensors based on Graphene Oxide-Molecular Imprinted Polymer

Herein, we report a controlled two-step synthesis technique to prepare Cu2O nanobeads over hydrogen exfoliated graphene (Cu2O NBs-HEG) and its application as an anode material in lithium ion battery. SEM images have proven, how the long copper hydroxide chains are cut shortened and ended up in copper oxide beads. The Cu2O beads are acting as a spacer in between the two dimensional planes and increasing the specific capacity of the battery almost three fold of the theoretical capacity of Cu2O. The oxidation states of copper are confirmed through X-ray photoelectron spectroscopy. Because of the synergetic effect of copper oxide and wrinkled graphene, the initial discharge capacity of the battery got enhanced to 2050 mAh/g. In order to get the charge transfer resistance of the electrode, the impedance spectroscopy is carried out and the results have been discussed. © 2016 Hydrogen Energy Publications, LLC.

Investigation of the role of Cu2O beads over the wrinkled graphene as an anode material for lithium ion battery

Abstract: In this work, we report a facile and one -step hydrothermal method to decorate SnO2 nanostructures on few-layered graphene for superior dopamine detection. The structural and morphological properties of the prepared nanohybrids illustrated the tetragonal crystal system of SnO2, reconstruction of graphene layers with oxygen containing functional groups, increased ID/IG ratio, and uniform decoration of SnO2 nanostructures on graphene layers. The prepared nanohybrids exhibited a high electrochemical activity toward dopamine oxidation in comparison with individual graphene sheets. This enhanced performance can be due to the presence of SnO2 nanostructures between the graphene layers, which efficiently avoid the restacking and increase the surface area accessibility. The fabricated nanohybrid-based sensor showed an increase in current with respect to the increased analyte concentration over the wide range of 0.005–0.20 × 10−6 M. The sensor exhibits excellent catalytic activity toward dopamine with the lowest detection limit of 6.3 nm. Further, the modified electrode exhibited good stability, reproducibility, and better recovery of 99 % in human urine samples suggesting the real-time usability of the sensor. Graphical Abstract: Schematic representation of SnO2 nanohybrids formation. The modified electrode exhibits superior catalytic activity. The oxidation peak current increased linearly in the concentration range of 0.005–0.019 × 10−6 M with LOD of 6.3 nm.[Figure not available: see fulltext.] © 2016, Springer Science+Business Media Dordrecht.

Journal of Applied Electrochemistry

One-step in situ hydrothermal preparation of graphene–SnO2 nanohybrid for superior dopamine detection

Reduced graphene oxide (rGO) and nitrogen doped graphene (NG) have been used as a support for decorating the platinum (Pt) and yttrium (Y) alloy (Pt3Y) nanoparticles. Pt3Y nanoparticles decorated graphene (Pt3Y/G) and Pt3Y nanoparticles decorated nitrogen doped graphene (Pt3Y/NG) have been applied as oxygen reduction reaction (ORR) electrocatalysts in proton exchange membrane fuel cells. The electrochemically active surface area has been measured by Cyclic Voltammetry (CV). The ORR activity has been investigated by polarization studies using fuel cell fixture. The enhanced catalytic activity of Pt3Y/NG towards ORR is due to homogeneous dispersion and optimum particle size of Pt3Y alloy nanoparticles over the surface of NG. This study revealed that, Pt3Y/NG is more ORR active than Pt3Y/G. Copyright © 2016 American Scientific Publishers.

Journal of Nanoscience and Nanotechnology

Investigation of electrocatalytic activity of pt-y alloy nanoparticles dispersed on nitrogen doped graphene for proton exchange membrane fuel cell

Platinum and platinum-iron alloy nanoparticles dispersed nitrogen-doped graphene as high performance room temperature hydrogen sensor

Nitrogen doped graphene has been synthesized using hydrothermal method and thermal solid state method with ammonia and melamine as nitrogen sources respectively. Platinum nanoparticles have been dispersed over these support materials using polyol method and these Pt loaded nitrogen doped graphene samples have been studied as electrocatalyst for oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell and for methanol oxidation reaction (MOR). Also, the role of multiwalled carbon nanotubes as a spacer which avoids face to face agglomeration of graphene sheets has also been studied for both the samples. The morphology and structure of the graphene based powder samples have been studied using X-ray diffraction, Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Half cell and full cell measurements have been performed on the samples for ORR and MOR. With the use of functionalized multiwalled carbon nanotubes, a maximum power density of 704 mW cm-2 and 650 mW cm-2 has been obtained with Pt dispersed nitrogen doped graphenes prepared by hydrothermal and thermal solid state methods respectively. The results have been compared with commercial Pt/C catalyst. © 2015 Hydrogen Energy Publications, LLC.

Nitrogen doped graphene prepared by hydrothermal and thermal solid state methods as catalyst supports for fuel cell

The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)-multiwalled carbon nanotubes (MWNTs)) hybrid structure (N-(G-MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO-negatively surface charged MWNTs) followed by the pyrolysis of these (rGO-MWNTs) hybrid structure-polymer composites. The N-(G-MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum-iron (Pt 3Fe) and platinum-cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt-TM alloy nanoparticle dispersed N-(G-MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt-C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications. © 2013 The Royal Society of Chemistry.

Nanoscale

Platinum-TM (TM = Fe, Co) alloy nanoparticles dispersed nitrogen doped (reduced graphene oxide-multiwalled carbon nanotube) hybrid structure cathode electrocatalysts for high performance PEMFC applications

A novel synthesis procedure is devised to obtain nitrogen-doping in hydrogen-exfoliated graphene (HEG) sheets. An anionic polyelectrolyte-conducting polymer duo is used to form a uniform coating of the polymer over graphene sheets. Pyrolysis of graphene coated with polypyrrole, a nitrogen-containing polymer, in an inert environment leads to the incorporation of nitrogen atoms in the graphene network with simultaneous removal of the polymer. These nitrogen-doped graphene (N-HEG) sheets are used as catalyst support for dispersing platinum and platinum-cobalt alloy nanoparticles synthesized by the modified-polyol reduction method, yielding a uniform dispersion of the catalyst nanoparticles. Compared to commercial Pt/C electrocatalyst, Pt-Co/N-HEG cathode electrocatalyst exhibits four times higher power density in proton exchange membrane fuel cells, which is attributed to the excellent dispersion of Pt-Co alloy nanoparticles on the N-HEG support, the alloying effect of Pt-Co, and the high electrocatalytic activity of the N-HEG support. A stability study shows that Pt/N-HEG and Pt-Co/N-HEG cathode electrocatalysts are highly stable in acidic media. The study shows two promising electrocatalysts for proton exchange membrane fuel cells, which on the basis of performance and stability present the possibility of replacing contemporary electrocatalysts. A novel method for the synthesis of Pt-Co alloy nanoparticles dispersed on nitrogen-doped graphene is developed. The as-prepared electrocatalysts show excellent oxygen reduction reaction (ORR) activity and stability in acidic medium for proton exchange membrane fuel cell (PEMFC) applications due to the high dispersion and alloying effect of Pt-Co, along with the inherent electrocatalytic activity of nitrogen-doped graphene as the supporting material. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Functional Materials

Novel platinum-cobalt alloy nanoparticles dispersed on nitrogen-doped graphene as a cathode electrocatalyst for PEMFC applications

Hybrid carbon nanostructures consisting of graphene nanoplatelets (GNPs) interspersed with multiwalled carbon nanotubes (MWCNTs) were synthesized by solution phase mixing of their parent aqueous dispersions. To further arrest the aggregation of GNPs, crystalline nanoparticles of a noble metal (Pt) were dispersed in situ by chemical reduction. This ensemble of the metal decorated hybrid structure was solubilized using Nafion and a simple drop casting method was employed to fabricate the sensor. In addition to the remarkable stability and repeatability, the sensor also showed an enhanced sensitivity of ∼17% to a low concentration of 4 vol.% hydrogen in air, at room temperature. The improved sensitivity due to Nafion solubilization could be explained by a dual mechanism of hydrogen dissociation. Variations in the sensor properties with change in hydrogen concentrations and temperature were studied. The kinetics of hydrogen adsorption in the sensor could be well explained by the Avrami-Erofeev model. From the Arrhenius plot of the rate constants, the activation energy was determined to be ∼24 kJ/(mol H). Effect of morphology of the bare hybrid structure was systematically investigated by varying the weight ratios of GNPs and MWCNTs. © 2010 Elsevier Ltd. All rights reserved.

Carbon

Hybrid carbon nanostructured ensembles as chemiresistive hydrogen gas sensors

Journal	Data powered by TypesetInternational Journal of Hydrogen Energy
Publisher	Data powered by TypesetElsevier Ltd
ISSN	03603199
Open Access	No